King Arthur is happily married to Queen Guenevere, but the arrival of handsome knight Sir Lancelot leads to infidelity and betrayal. For a time, the king refuses to believe his wife is having an affair, but the lovers are betrayed by Arthur's son, the conniving Mordred. Oscar-winning musical based on the Arthurian legend, starring Richard Harris, Vanessa Redgrave, Franco Nero, David Hemmings and Lionel Jeffries.

The plot of his illegitimate son Mordred to gain the throne, and Guinevere's growing attachment to Sir Lancelot, threatens to topple King Arthur and destroy his "round table" of knights.